1. Field of the Invention
The present invention relates to cellular phones, personal digital assistants (PDAs), tablet PCs, mobile terminal devices such as electronic book terminals, storage media holding computer programs preferably for use in the mobile terminal devices, and methods for display control of the mobile terminal devices.
2. Disclosure of Related Art
Conventionally, a mobile terminal device is equipped with various application programs (hereinafter, referred to as simply “applications”). When an application is executed, an execution screen for the application is displayed on a display surface of a display.
Such a mobile terminal device may be configured such that the display direction of the execution screen is changed with respect to the mobile terminal device according to the posture of the mobile terminal device, for improvement of convenience of users. For example, the mobile terminal device is provided with an acceleration sensor, whereby it is determined whether the mobile terminal device is in portrait or landscape orientation with respect to the ground, based on a gravity acceleration detected by the acceleration sensor. Accordingly, the execution screen is vertically displayed on the display surface, regardless of whether the mobile terminal device is in portrait or landscape orientation.
In the foregoing configuration, however, if the posture of the mobile terminal device is not changed with respect to the user but is changed with respect to the ground because a user lies down with the mobile terminal device in hand, the display direction of the execution screen may be switched without discretion in a manner for which it is difficult for the user to view the screen.
Accordingly, it is considered that a mobile terminal device is configured to suppress switching of display directions of the execution screen as necessary. In this case, it is desired to suppress switching of display directions without requiring the user's time and effort as much as possible.